It depends on what you are looking for: and I don't even mean a particular model.
Time for a long spiel. Ignore this if you care not for ramblings...
For example, I wasn't sure if the Speedy 25 was a good size and whether I could stand the hand-held carry or not. Instead of going straight-in with a new bag and using it (it's sort of like buying a new car...once you drive it off the lot, you lose a good chunk of its worth when you sell it, again) I try to find many cheaper alternatives to simulate the "problem" I am trying to solve. I tried over and over again to find a bag the exact size in all dimensions with a zipper-top that doesn't go down the sides (a la empreinte speedy) as the Speedy 25. Many cheap (I'm talking $20-$50 cheap) bags come close to the size but doesn't solve my exact problem: they tend to be much heavier, their linings tend to be loose from the exterior wall and loose linings irritate me to no end, the style is not quite the same, be shorter, not quite as deep, handles didn't have hinges or were floppy unrolled handles, etc etc. So, then, without plunking down 1500USD for a Speedy 25 Bandouliere just to check the size, strap, vachetta vs treated leather etc etc, I ran my experiment on a preloved Speedy. This would be the only reason I'd get a model that is still in production. I bought a monogram canvas Speedy 25 (classic style) and a vachetta strap used on eBay from one of the reputable Japanese sellers. I spent $270+$130 on two items that will last many years to come, is already soft (the strap), and I can beat up and scratch up against my stucco wall (I often run up against it while trying to walk along the side of my garage) without caring because I spent so little on it. The $270 on the bag would have easily been what I would have lost selling back a bandouliere bag that I possibly wouldn't have liked. And with that amount spent and time spent researching, I also got to figure out many other points:
1) I am not particularly fond of super dark handles,
2) I am not fond of handles that have darkened to any extent only in the middle,
3) I don't like cracked/dry leather,
4) monogram canvas bags are easier to find used much cheaper instead of azur and de,
5) I do not like used azur bags because I have seen far too too too many of these with yellowed canvas,
6) the 25 is a good size for my own belongings but is a hassle when I add my kid's belongings,
7) the little pocket in the Speedy is acceptable to me,
8) epi leather on bags can crease badly in the cross-grain direction and also rub off at the edges in a visually displeasing manner,
9) the classic Speedy with strap method of faking a bandouliere gets irritating when the bag twirls around or when I have to open the last 1/3 of the zipper,
10) I only like to use the top-handles when stepping out of the car and have to pull the bag out of the car after which I switch to the shoulder strap,
11) but, I don't dislike this combination enough to stop using it
etc.
I think it was a great experiment/learning experience that I didn't spend additional money on. On the other hand, I later bought a new Speedy Bandouliere 30 in DE from the LV website for when I need to tote my kid's stuff with me. I learned more things from having THAT one that I couldn't learn from the 25/strap combo (i.e. the newer zippers and the zipper on the 30 size is annoying to zip up, longer size makes part of the bag fold a bit if I don't fill up both ends of the bag with items/clothes, the treated leather will still chip, DE leather strap is not as convenient to fold/pool around the bag when putting it down, etc.)
I think I would buy used (for a model in production) like this, again, only for the delightful and neverfull -- I hate open top bags, normally, and would have to test that out.
On a side note: I got my MIL a preloved Speedy 30 (classic) in monogram and azur both in like new/excellent condition from
Fashionphile and Yoogi's. I saw no reason to spend more when I could get 2 bags for a little more than the price of 1.